The Structure of the Protein Phosphatase 2A PR65/A Subunit Reveals the Conformation of Its 15 Tandemly Repeated HEAT Motifs

Groves, Matthew R.; Hanlon, Neil; Turowski, Patric; Hemmings, Brian A.; Barford, David

doi:10.1016/s0092-8674(00)80963-0

Cited by 400 publications

(349 citation statements)

References 60 publications

Supporting

Mentioning

329

Contrasting

Unclassified

Order By: Relevance

“…Domain searches also predicted the presence of five HEAT (huntingtin-elongation-A subunit-TOR) motifs (Groves et al, 1999) distributed throughout KapI as indicated in Fig. 1(a) (dark rectangles).…”

Section: Resultsmentioning

confidence: 98%

KapI, a non-essential member of the Pse1p/Imp5 karyopherin family, controls colonial and asexual development in Aspergillus nidulans

Etxebeste

Markina-Iñarrairaegui

Garzia

et al. 2009

Microbiology

View full text Add to dashboard Cite

Asexual development in the filamentous fungus Aspergillus nidulans is governed by the timely expression and cellular localization of multiple transcription factors. Hence, factors mediating import and export across the nuclear pore complexes (karyopherins) are expected to play a key role in coordinating the developmental programme. Here we characterize KapI, a putative homologue of the Saccharomyces cerevisiae Kap121/Pse1p karyopherin. KapI is a non-essential importin-b-like protein located in the nucleus during vegetative growth and conidiophore development. The DkapI phenotype is aconidial with many aerial hyphae. This phenotype can be suppressed under abiotic stress. In this regard, it resembles that of the null allele of the bZIP transcription factor FlbB. However a DflbB; DkapI double mutant exhibited an additive phenotype with totally impaired conidiation, unresponsive to abiotic stress. In contrast to DflbB, the null kapI mutant is not a fluffy-low-bristle expression mutant. Taken together the findings indicate that KapI is required during asexual development, mediating the nuclear transport of factors acting in a different pathway(s) from those involving the upstream developmental activators.

show abstract

Section: Resultsmentioning

confidence: 98%

KapI, a non-essential member of the Pse1p/Imp5 karyopherin family, controls colonial and asexual development in Aspergillus nidulans

Etxebeste

Markina-Iñarrairaegui

Garzia

et al. 2009

Microbiology

View full text Add to dashboard Cite

show abstract

“…Recent structural studies of PI3K␥ show that it contains many modular regions including a helical domain (also called a HEAT sequence motif) (14) that could be involved in proteinprotein interactions (24,25). Since the HEAT sequence is common to PI3K␣, -␤, and -␥ isoforms, it is possible that this is the common interacting domain for all PI3Ks.…”

Section: Discussionmentioning

confidence: 99%

Agonist-dependent Recruitment of Phosphoinositide 3-Kinase to the Membrane by β-Adrenergic Receptor Kinase 1

Prasad¹,

Barak

Rapacciuolo³

et al. 2001

Journal of Biological Chemistry

169

170

View full text Add to dashboard Cite

Agonist-dependent desensitization of the ␤-adrenergic receptor requires translocation and activation of the ␤-adrenergic receptor kinase1 by liberated G␤␥ subunits. Subsequent internalization of agonist-occupied receptors occurs as a result of the binding of ␤-arrestin to the phosphorylated receptor followed by interaction with the AP2 adaptor and clathrin proteins. Receptor internalization is known to require D-3 phosphoinositides that are generated by the action of phosphoinositide 3-kinase. Phosphoinositide 3-kinases form a family of lipid kinases that couple signals via receptor tyrosine kinases and G-protein-coupled receptors. The molecular mechanism by which phosphoinositide 3-kinase acts to promote ␤-adrenergic receptor internalization is not well understood. In the present investigation we demonstrate a novel finding that ␤-adrenergic receptor kinase 1 and phosphoinositide 3-kinase form a cytosolic complex, which leads to ␤-adrenergic receptor kinase 1-mediated translocation of phosphoinositide 3-kinase to the membrane in an agonist-dependent manner. Furthermore, agonist-induced translocation of phosphoinositide 3-kinase results in rapid interaction with the receptor, which is of functional importance, since inhibition of phosphoinositide 3-kinase activity attenuates ␤-adrenergic receptor sequestration. Therefore, agonistdependent recruitment of phosphoinositide 3-kinase to the membrane is an important step in the process of receptor sequestration and links phosphoinositide 3-kinase to G-protein-coupled receptor activation and sequestration.Phosphoinositide 3-kinases (PI3Ks) 1 are a family of enzymes that can be divided into three classes based on their structure and substrate specificity (1). The class I PI3Ks are heterodimeric enzymes consisting of catalytic and regulatory subunits that are divided into the subgroups I A and I B . The class I A PI3K (consisting of p110 ␣, ␤, and ␦ catalytic subunits) associates with the p85 regulatory subunit and is essential for coupling signals through receptor tyrosine kinases (1). The class I B PI3K (p110␥ catalytic subunit) associates with the p101 adaptor subunit and is activated by ␤␥ subunits of G-proteins (2). Stimulation of a variety of G-protein-coupled receptors (GPCRs) through G␤␥-mediated activation of PI3K␥ leads to an increase in the level of 3Ј-phosphorylated phosphatidylinositol (PtdIns), which in turn mediates diverse cellular effects including cell proliferation, cell survival, cytoskeletal rearrangements, and endocytosis (3).The exposure of a GPCR to agonist produces rapid attenuation of its signaling ability that involves uncoupling of the receptor from its cognate heterotrimeric G-protein. The cellular mechanism mediating agonist-specific or homologous desensitization is a two-step process in which agonist-occupied receptors are phosphorylated by a G-protein-coupled receptor kinase and then bind arrestin proteins (4). Homologous desensitization of agonist-occupied ␤-adrenergic receptors (␤ARs) occurs after translocation of G-protein-coupled recep...

show abstract

“…Residues 1-321 are organized in classical HEAT repeats 13 with a total of 16 helices. Instead of forming a single long, curved structure as found in PP2A 14 , the HEAT domain of eEF3 makes a sharp bend after the first 10 helices. The HEAT domain is connected through a flexible linker to a four-helix bundle (4HB domain; residues 336-413), which packs against the bottom of the concave face of the HEAT domain.…”

Section: Crystal Structure Of Eef3mentioning

confidence: 94%

Structure of eEF3 and the mechanism of transfer RNA release from the E-site

Andersen

Becker

Blau

et al. 2006

Nature

147

164

View full text Add to dashboard Cite

Elongation factor eEF3 is an ATPase that, in addition to the two canonical factors eEF1A and eEF2, serves an essential function in the translation cycle of fungi. eEF3 is required for the binding of the aminoacyl-tRNA-eEF1A-GTP ternary complex to the ribosomal A-site and has been suggested to facilitate the clearance of deacyl-tRNA from the E-site. Here we present the crystal structure of Saccharomyces cerevisiae eEF3, showing that it consists of an amino-terminal HEAT repeat domain, followed by a four-helix bundle and two ABC-type ATPase domains, with a chromodomain inserted in ABC2. Moreover, we present the cryo-electron microscopy structure of the ATP-bound form of eEF3 in complex with the post-translocational-state 80S ribosome from yeast. eEF3 uses an entirely new factor binding site near the ribosomal E-site, with the chromodomain likely to stabilize the ribosomal L1 stalk in an open conformation, thus allowing tRNA release.Protein synthesis requires, in general, only two canonical GTPase elongation factors. eEF1A (known as EF-Tu in prokaryotes) recruits cognate aminoacyl-tRNAs to the A-site of the ribosome, and, after peptidyl transfer, eEF2 (EF-G in prokaryotes) catalyses translocation of the messenger RNA and the transfer RNAs from the A-and P-sites to the P-and E-sites. In contrast to the canonical factors, eEF3 has an ATPase activity that is stimulated by ribosomes. It interacts with both ribosomal subunits 1-3 , competes with eEF2 for binding to ribosomes, and stimulates eEF1A-dependent binding of cognate aminoacyltRNA to the ribosomal A-site 1,4 . Because, according to the allosteric three-site model of the ribosomal elongation cycle, E-site release is required for efficient A-site binding, it has been suggested that eEF3 functions as a so-called 'E-site factor' 4,5 . Moreover, ATP hydrolysis by eEF3 is required in every elongation cycle to allow chasing of deacyltRNA from the E-site 4 .eEF3 belongs to the family of ABC (ATP-binding cassette) proteins that includes proteins involved in transport across membranes, DNA repair, and translation. The membrane proteins of this class especially represent important targets for development of novel therapeutic strategies. The proteins contain ATP/ADP-binding ABC domains, which convert chemical energy derived from binding of ATP or its hydrolysis into a 'powerstroke' of mechanical energy 6 . ABC proteins function as either homodimers or as twin-cassette proteins with two ABC domains within the same polypeptide.The ribosome exhibits very dynamic behaviour, such as the ratchet movement 7 or the movement of the L1 and the L7/L12 stalks [8][9][10][11] . Hence, an intriguing question is how the interaction of eEF3 with the ribosome is correlated with its dynamic properties as an ABC protein, and how the energy derived from binding/hydrolysis of ATP is used for its function. Crystal structure of eEF3Three crystal structures of residues 1-980 of eEF3 in the apo state (2.7 Å ), in complex with ADP (2.4 Å ), or in complex with the nonhydrolysable ATP analogue ADPNP (3...

show abstract

The Structure of the Protein Phosphatase 2A PR65/A Subunit Reveals the Conformation of Its 15 Tandemly Repeated HEAT Motifs

Cited by 400 publications

References 60 publications

KapI, a non-essential member of the Pse1p/Imp5 karyopherin family, controls colonial and asexual development in Aspergillus nidulans

KapI, a non-essential member of the Pse1p/Imp5 karyopherin family, controls colonial and asexual development in Aspergillus nidulans

Agonist-dependent Recruitment of Phosphoinositide 3-Kinase to the Membrane by β-Adrenergic Receptor Kinase 1

Structure of eEF3 and the mechanism of transfer RNA release from the E-site

Contact Info

Product

Resources

About